Scissor jacks are well known and most commonly used for lifting vehicles. This type of jack is also sometimes referred to as a screw-operated jack. The basic design and principle of operation has been used for some time.
Improvements to these jacks have generally related to the screw-threaded shaft or to the trunnions which connect the shaft into the assembly. A relatively large amount of force is required to lift a load with these jacks or, alternatively, the lifting rate is made slower so that less force is required.
Where jacks are used in off-road conditions they are often subjected to more severe mechanical stresses. These can increase the chance of component structural failure.
The problems with inefficient lifting and mechanical failure are emphasized where heavier vehicles need to be lifted. In addition to some of the larger four wheel drive vehicles on the market, the military also generally use heavier vehicles.